JP2000065726A - Droplet detection method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet detection method with improved sensitivity without allowing detection light to interfere with a driver. SOLUTION: Light emitted from a light-emitting device 4 is guided into a light-guiding body 7, totally reflected in the light-guiding body 7, and then guided into front glass G. Then, light being guided into the front glass G is repeatedly and totally reflected in the front glass G and then received by a photo detector 5. In this case, a raindrop adheres to the outer surface of the front glass G, and when the adhesion point is the total reflection point of light, light being guided into the front glass G is not totally reflected and escapes from the front glass G. As a result, the quantity of light being received by the photo detector 5 decreases, thus detecting the adhesion of raindrop and outputting a signal for driving a windshield wiper or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for detecting a raindrop adhering to, for example, a windshield of an automobile and driving a wiper or the like accordingly.

[0002]

2. Description of the Related Art Optical type liquid drop detecting device (rain sensor)
The present applicant has proposed Japanese Patent Application No. 9-68616. This device has a configuration in which a light emitting element and a light receiving element are attached to a light guide fixed to one surface side of a glass plate, and light rays emitted from the light emitting element are introduced into the glass plate through the light guide,
When light rays totally reflected on the inner surface of the glass plate enter the light-receiving element, the amount of total reflected light is reduced if water droplets are present at the total reflection point. This is to detect whether or not it has been done.

[0003]

When the above-described liquid drop detecting device is applied to an automobile, the liquid drop detecting device is mounted on the inner surface of a windshield, but in this case, operation is not hindered. Although it is necessary that the sensitivity and the sensitivity of the detection be not reduced, the application to an automobile has conventionally been experimental, and sufficient consideration has not been given to these.

[0004]

According to the present invention, there is provided a droplet detecting method for guiding light emitted from a light emitting means into a glass plate and receiving light totally reflected on an inner surface of the glass plate. In a droplet detection method that detects the presence or absence of a droplet attached to a glass plate by detecting with an element,
The wavelength of the light emitted from the light emitting means is from 700 nm to 780
nm.

[0005] Further, a droplet detecting device according to the present invention comprises a light emitting means, a glass plate to which light emitted from the light emitting means is guided,
A light receiving element for detecting light totally reflected on the inner surface of the transparent substrate, the liquid drop detecting device is mounted, for example, on the indoor side surface of a portion of the front glass of an automobile where a blur pattern is provided. And the light emitting means has a wavelength of 700
nm to 780 nm.

[0006] The wavelength of light used for detection is 700 nm to 78 nm.
The reason why the wavelength is set to 0 nm is that, when the wavelength is shorter than 700 nm, the relative luminous efficiency gradually increases as shown in the table, and the detection light is easily recognized by the naked eye, which is obstructive.

[0007]

【table】

On the other hand, recent windshields use a relatively large amount of iron component for the purpose of cutting off ultraviolet rays and absorbing heat rays. And the absorption range of iron is 900-1000n
m, the absorption in the infrared region exceeding 780 nm increases, and the sensitivity decreases. In particular, if the number of measurement points (total reflection points) of the droplet detection device is increased to improve the reliability of detection, the number of total reflections must be two or more. However, as the number of total reflections increases, the light attenuates,
Reliability decreases.

Further, recent windshields for automobiles include:
Many people have provided an anti-glare blur on the upper side. The line segment a in FIG. 3 shows the relationship between the wavelength and the transmittance of the automotive windshield using polyvinyl butyral as the interlayer, and the line segment b shows the wavelength and the transmittance at the blurred P portion of the automotive windshield. 6 is a graph showing a relationship with the graph. From this graph, it can be seen that, in the blurred portion, light having a wavelength of 470 to 700 nm is selectively absorbed. That is, a droplet detecting device is provided inside a windshield in which a blur is provided in the intermediate film, and a wavelength of 4
When a light beam of 70 to 700 nm is used, the detection light is absorbed in the blurred portion, and the sensitivity is greatly reduced.

Therefore, in the present invention, in the range of visible light, the relative luminous efficiency is small and does not cause any obstruction, and the absorption in glass is small, 700 nm to 780.
nm light was used.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a perspective view showing an example in which the droplet detection device according to the present invention is applied to an automobile, and FIG.
1 is a cross-sectional view of a state in which a droplet detection device according to the present invention is mounted on a windshield of an automobile.

The windshield G of an automobile is formed by laminating an inner glass plate G1 and an outer glass plate G2 via an interlayer film C. In particular, a blur pattern Gr is formed on the upper side of the front glass G. The blur pattern Gr is provided between the inner glass plate G1 and the outer glass plate G2 so as to overlap the interlayer film C.

Further, a blur pattern Gr of the windshield G
The droplet detection device 1 according to the present invention is provided at a position hidden by the rear-view mirror M on the indoor side surface of the portion provided with.

The droplet detecting device 1 is configured by housing a plurality of members in a case 2, and the case 2 includes a base 2 a made of aluminum or resin fixed to the indoor side surface of the front glass G with an adhesive sheet 3, A cover 2b is attached to the base 2a with screws or the like. The attachment portion of the cover 2b to the base 2a may be at both ends in the length direction, but only one end is fixed with a screw, and the other end is free in the length direction by simply inserting it, and can follow a temperature change or the like. You may do so.

A holder 2c is fixed between the base 2a and the cover 2b. A light emitting element 4 for emitting light of 700 nm to 780 nm is held at one end of the holder 2c in the longitudinal direction. Holds a light receiving element 5, and a light guiding means 6 for guiding light emitted from the light emitting element 4 to the light receiving element 5 is provided between the base 2a and the holder 2c.

The light guide means 6 includes a glass light guide 7 on which light emitted from the light emitting element 4 is incident, a glass light guide 8 for allowing light to enter the light receiving element 5, and these light guides 7. ,
8, a light guide 9 made of glass disposed so that both ends thereof overlap with each other, between the light guides 7, 8 and the light guide 9, and between the light guide 9 and the windshield G. Are interposed between the silicone members 10.

The silicone member 10 is an elastic body having a refractive index substantially equal to that of the glass light guides 7, 8, 9 and the front glass G. The thickness of the silicone member 10 is such that the cover 2b is attached to the base 2a. Between the light guides 7, 8, 9 and the silicone member 10, and between the light guides 7, 8, 9 and the silicone member 10, and between the windshield G and the silicone member 10, air layers are formed. Set dimensions that do not remain. That is, if the air layer remains in the above-mentioned portion, the light is totally reflected without transmitting, the light from the light emitting element 4 does not reach the windshield G, and the light totally reflected in the windshield G is received. The result is that the element 5 is not reached.

For the same reason, a silicone having a thickness that prevents the air layer from being formed between the light guide 9 and the light receiving element 5 by being slightly crushed during the assembly between the light receiving element 5 and the light guide 9. Member 1
0 is interposed. Instead of the silicone member 10, a nonvolatile liquid having a refractive index substantially equal to that of the light guides 7, 8, 9 and the front glass G may be used.

As described above, by separating the light guides 7 and 8, a space 11 is formed at the center. If the space 11 is left as it is, condensation may occur. Therefore, it is preferable that a desiccant is enclosed.

The light guides 7, 8 are accommodated in a window 13 formed in a sheet-shaped light shielding member 12, and are provided in the light guides 7, 8.
A reflection film 14 made of a metal thin film is provided at an appropriate position on the surfaces of 8, 9. The reflective film 14 does not need to be particularly provided when the light is incident at an angle at which the light is totally reflected.

On the other hand, a diffraction grating 15 is provided on the upper surface of the light guide 7. The diffraction grating 15 is for introducing light from the light emitting element 4 into the light guide 7 at a predetermined angle and for reflecting a part of the light from the light emitting element 4 to the light receiving element 16 for monitoring.

As a method of manufacturing the diffraction grating, it is conceivable to use an ablation phenomenon in which a glass surface is partially evaporated by a laser beam. The ablation phenomenon is a phenomenon that occurs when glass absorbs laser light energy. Silver is contained in the form of Ag atoms, Ag colloids or Ag ions from the surface of the glass substrate to a predetermined depth, and the silver concentration is further processed by laser processing. If the concentration on the surface is highest and the concentration gradient is set so that the silver concentration gradually decreases to a predetermined depth, abrasion phenomena occur sequentially from the surface layer to the inside, causing cracks and chipping Fine processing can be performed without any problems.

In the above, the light emitted from the light emitting element 4 is introduced into the light guide 7 via the diffraction grating 15 and totally reflected in the light guide 7, and then comes into close contact with the light guide 7 and The light is introduced into the windshield G through the silicone member 10 having the same refractive index, the light guide 9, and the silicone member 10 between the light guide 9 and the windshield G. Then, the light introduced into the windshield G repeats total reflection in the windshield G, and then the silicone member 10, the light guide 9, and the light guide 9 between the light guide 9 and the windshield G are formed. Light guide 8
The light is received by the light receiving element 5 through the silicone member 10 and the light guide 8 between them. At this time, when raindrops adhere to the outer surface of the windshield G and the point of attachment is the point of total reflection of the light, the light introduced into the windshield G passes through the windshield G without being totally reflected. I will. As a result, the amount of light received by the light receiving element 5 decreases, thereby detecting that raindrops have adhered and outputting a signal for driving a wiper or the like.

[0024]

According to the present invention as described above,
Wavelength 70 as detection light of a droplet detection device applied to an automobile
Since the light beam of 0 nm to 780 nm is used, the detection light does not obstruct the driver, and the degree of absorption of the light beam to the light receiving means is small since the degree of absorption is small in the glass and the blurred portion. Strong, sensitivity is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example in which a droplet detection device according to the present invention is applied to an automobile.

FIG. 2 is a cross-sectional view of a state where the droplet detection device according to the present invention is mounted on a windshield of an automobile.

FIG. 3 is a graph showing the relationship between the transmittance and the wavelength when a glass plate and a transparent intermediate film are combined and when a blurred pattern is provided on the glass plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Droplet detection device, 2 ... Case, 2a ... Base, 2b ...
Cover 3 Adhesive sheet 4 Light emitting element 5 Light receiving element 6 Light guide means 7, 8, 9 Light guide 10 Silicone member 15 Diffraction grating G Front glass G1
... Inner glass plate, G2 ... Outer glass plate, Gr ... Blur pattern, C ... Interlayer film.

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Keiji Tsuneomo 3-5-1, Doshumachi, Chuo-ku, Osaka-shi, Osaka F-term in Nippon Sheet Glass Co., Ltd. (reference) 2G059 AA05 BB04 EE02 FF01 GG02 HH02 HH06 JJ14 JJ21 KK01 MM05 PP02 3D025 AA01 AB01 AC01 AD02 AG42

Claims (3)

[Claims] 1. A light emitting device, wherein light emitted from a light emitting means is guided into a glass plate, and light totally reflected on an inner surface of the glass plate is detected by a light receiving element to detect the presence or absence of a droplet attached to the glass plate. The method for detecting a droplet according to claim 1, wherein the wavelength of the light emitted from the light emitting means is set to 700 nm to 780 nm. 2. A droplet detecting apparatus comprising: a light emitting means; a glass plate to which light emitted from the light emitting means is guided; and a light receiving element for detecting light totally reflected on an inner surface of the transparent substrate, wherein the light emitting means is A droplet detection device that emits light having a wavelength of 700 nm to 780 nm. 3. A droplet detecting device according to claim 2, wherein said droplet detecting device is attached to an interior side surface of a portion of the front glass of the automobile where the blur pattern is provided. apparatus.